The field of the present invention is one-way valves and pumps employing such valves.
One-way valves are typically simple mechanisms including a passage, a valve seat within that passage and a valve element capable of sealing with the valve seat. The valve element in the simplest of such devices often is defined by a ball, a hinged flap or a “mushroom”. The mushroom is commonly at least a portion of a ball on the end of a shaft with the shaft being slidably mounted coaxially with the centerline of the valve seat. Such elements are typically actuated by pressure and flow with resistance to opening provided by gravity, back pressure and/or resilient elements.
The mounting of such one-way valves, because of their simplicity, frequently reflect the structures with which they are associated. Where such valves are separate subassemblies, radially extending mounting flanges about the ends of the valve passage are common. Such flanges mate with like flanges on associated equipment and are held in place by conventional mechanisms such as band clamps and bolts. Because of the simplicity of one-way valves, they are frequently incorporated into the body of the adjacent apparatus.
Air driven double diaphragm pumps provide one example of a major use of one-way valves. Such pumps include a central air manifold and air valve, air chambers to either side of the air manifold and pump chambers to either side of the air chambers. Diaphragms are placed between the air chambers and pump chambers to complete the horizontal stack of components. Two one-way valves are associated with each pump chamber, an intake valve oriented below and an exhaust valve oriented above the pump chamber. The pump chamber defines passageways with which valve elements and valve seats are placed. Mounting flanges are located at the intake port before the intake one-way valve and at the terminus of the exhaust port after the one-way exhaust valve. Again, clamp bands or bolts are employed to associate the mounting flanges with intake and exhaust piping.
Of particular interest with air driven diaphragm pumps arranged in a horizontal stack as described above, intake and exhaust manifolds are associated with the pumps and span across the pump to the corresponding intake/exhaust ports. Care must be taken in the parts selection and assembly of such devices because the stack as measured between the corresponding ports on either end thereof has a cumulative tolerance which can cause misalignment of the manifold mounting flanges with the port mounting flanges. In conventional pumping applications, such possible mismatches are considered tolerable unless so great that the seal is ineffective and results in leakage.
The aforementioned air driven double diaphragm pumps have been experiencing more and more utility in food processing and other processing operations which require a very clean environment. With food processing, design challenges can be compounded because the food itself becomes a contaminant with time. Consequently, even the pumped material is to be periodically eliminated from the pump environment. These requirements dictate proper sealing and the elimination of quiescent areas in flow streams. As a result, the misalignment mentioned above, tolerable in most circumstances, becomes less tolerable in such applications as food processing where such misalignments can cause small quiescent areas and small cavities in the joints between components. Further, to insure ultimate ability to clean all components, the one-way valves on sanitary equipment are more typically removable rather than integrally formed with the pump cavities.